Unsaturated polyester resins modified with perfluoropolyethers

Telechelic macromers based on hydroxyterminated perfluoropolyethers (HO-RH-PFPE-RH-OH) with different molecular weights were used for the preparation of fluorine-containing unsaturated polyester resins (FUPR). The products resulting from the reaction of the monomers usually employed for the preparation of unsaturated polyesters with HO-RH-PPPE-RH-OH were in any case milky liquids. The degree of reaction of the hydroxyl terminal groups of HO-RH-PFPE-RH-OH was monitored by 1H-NMR analysis on the fractions collected after sedimentation experiments; amount and composition of the sediment and sedimentation rate were found dependent on both the molecular weight of fluorinated macromer and the method used for polyesterification. The molecular weight of HO-RH-PFPE-RH-OH and the reaction conditions had also a strong influence on the final morphology of crosslinked polymers. A very poor interphase adhesion was observed when unreacted HO-RH-PFPE-RH-OH was blended with the unsaturated polyester. On the contrary, when the fluorinated macromer was allowed to react during polyesterification, the adhesion of the fluorine-rich dispersed phase to the unsaturated polyester matrix was good for low molecular weight HO-RH-PFPE-RH-OH and when the fluorinated prepolymer had been modified by a previous reaction with chlorendic anhydride, but it was poor, as for unreacted macromers, for high molecular weight HO-RH-PFPE-RH-OHs. FUPRs prepared using a low molecular weight HO-RH-PFPE-RH-OH exhibited a significant improvement of the flexural strength even at very low level of addition (3% by wt). © 1998 John Wiley & Sons, Inc

Unsaturated polyester resins modified with perfluoropolyethers

Telechelic macromers based on hydroxyterminated perfluoropolyethers (HO-R-H-PFPE-R-H-OH) with different molecular weights were used for the preparation of fluorine-containing unsaturated polyester resins (FUPR). The products resulting from the reaction of the monomers usually employed for the preparation of unsaturated polyesters with HO-R-H-PFPE-R-H-OH were in any case milky liquids. The degree of reaction of the hydroxyl terminal groups of HO-R-H-PFPE-R-H-OH was monitored by H-1-NMR analysis on the fractions collected after sedimentation experiments; amount and composition of the sediment and sedimentation rate were found dependent on both the molecular weight of fluorinated macromer and the method used for polyesterification. The molecular weight of HO-R-H-PFPE-R-H-OH and the reaction conditions had also a strong influence on the final morphology of crosslinked polymers. A very poor interphase adhesion was observed when unreacted HO-R-H-PFPE-R-H-OH was blended with the unsaturated polyester. On the contrary, when the fluorinated macromer was allowed to react during polyesterification, the adhesion of the fluorine-rich dispersed phase to the unsaturated polyester matrix was good for low molecular weight HO-R-H-PFPE-R-H-OH and when the fluorinated prepolymer had been modified by a previous reaction with chlorendic anhydride, but it was poor, as for unreacted macromers, for high molecular weight HO-R-H-PFPE-R-H-OHs. FUPRs prepared using a low molecular weight HO-R-H-PFPE-R-H-OH exhibited a significant improvement of the flexural strength even at very low level of addition (3% by wt)

Note Illustrative della Carta geologica d'Italia alla scala 1:50.000, F. 118 Milano, Servizio Geologico d'Italia - ISPRA

Note illustrative redatte per il Foglio geologico n.118 Milano della Carta Geologica d'Italia alla scala 1:50.000. 224 pp

Il progetto HELI-DEM (Helvetia-Italy Digital Elevation Model): scopi e stato di attuazione

The HELI-DEM(Helvetia Italy Digital Elevation Model) project aims to create a unified digital model of heights for the alpine and subalpine zones along the border between Italy and Swizzerland. This model should be properly geo-referenced and produced combining in a single model all the available information. The project is divided into nine Work Packages (WPs), for a total duration of 30 months. The project is now in the ninth month. This paper discusses the purposes of HELI-DEM, presents the different WPs and the present state of the projec

Glutamine Synthetase in Legumes: Recent Advances in Enzyme Structure and Functional Genomics

Abstract: Glutamine synthetase (GS) is the key enzyme involved in the assimilation of ammonia derived either from nitrate reduction, N2 fixation, photorespiration or asparagine breakdown. A small gene family is encoding for different cytosolic (GS1) or plastidic (GS2) isoforms in legumes. We summarize here the recent advances carried out concerning the quaternary structure of GS, as well as the functional relationship existing between GS2 and processes such as nodulation, photorespiration and water stress, in this latter case by means of proline production. Functional genomic analysis using GS2-minus mutant reveals the key role of GS2 in the metabolic control of the plants and, more particularly, in carbon metabolism

Il progetto HELI-DEM (Helvetia-Italy Digital Elevation Model): scopi e stato di attuazione

The HELI-DEM(Helvetia Italy Digital Elevation Model) project aims to create a unified digital model of heights for the alpine and subalpine zones along the border between Italy and Swizzerland. This model should be properly geo-referenced and produced combining in a single model all the available information. The project is divided into nine Work Packages (WPs), for a total duration of 30 months. The project is now in the ninth month. This paper discusses the purposes of HELI-DEM, presents the different WPs and the present state of the project